Lesson 8.4: Help for Exercises 39-44 on page 485
For all of the exercises except for Exercise 43, you will write a proportion based on corresponding side lengths of the two similar triangles. Then you can use the Cross product property on page 459 to solve the proportion and find the value of the variable.
For Exercise 43, you can use the fact that corresponding angles of similar triangles are congruent. Look carefully at the diagram to decide which angle in the smaller triangle corresponds to the 45° angle in the larger triangle.
For Exercise 44, the similar triangles overlap, so you may want to separate them. Sketch the two triangles and label all known side lengths before you write and solve a proportion.